Moses at Sinai: lithograph by F. W. McCleave, 1877
There is a common tendency—at least, it seems to me very widespread—to equate religion with religious belief. Whatever convenience such an equation may have for thinking about Christianity, it makes nonsense of Judaism. To say that someone “practices Judaism” is perfectly intelligible; to say that someone “believes Judaism” is a bizarre combination of words.
Nonetheless, it is plain that there are Jewish beliefs, that is, beliefs characteristic of Judaism, or at least of this or that variety or denomination of Judaism. Some of these beliefs may even be considered to be foundational, in the sense that they provide a rationale for religious observances. The nineteenth-century movement to preserve traditional Jewish observances called itself “Orthodoxy”—“correct belief”—for a reason: it also meant to preserve, or rather to establish, a body of specifically Jewish doctrine or dogma. 
But what sorts of beliefs may be counted as religious ones? Consider the following three propositions as examples:
- The Torah (i.e., the Pentateuch) was written down in the Sinai desert by Moses more than three thousand years ago.
- The Torah was dictated to Moses by God.
- God exists.
The first proposition does not imply, or at least need not be interpreted as implying, any supernatural element. It concerns a matter of historical, or more broadly natural fact.
The second proposition has both a natural and a supernatural element. The natural element is just what is stated in (1), that the Torah was written down by Moses more than three thousand years ago. The supernatural element is the idea that this writing-down was a taking of divine dictation. (I use the phrase “written down” rather than simply “written” so as not to exclude that idea a priori: to say that the Torah was written by Moses might be understood to imply that he was its author rather than merely, as per (2), its original scribe.)
The third proposition I take to be of purely supernatural significance. Of course, I have not tried to define the terms “natural” and “supernatural,” but rather than take on that difficult task, I will simply take the two terms to be sufficiently well understood for my purposes. My three examples are meant to illustrate the distinction that I propose among three kinds of religious belief: (1) natural beliefs, (2) mixed natural–supernatural beliefs, and (3) purely supernatural beliefs.
The points that I want to make about these three kinds of belief are the following. First, while people tend to identify religious belief with beliefs of the third type, such as the belief that God exists or beliefs about the divine nature, a very large part of religious belief consists of natural elements. In consequence, many religious beliefs are not essentially religious, in the sense that they are such that it is possible for someone to believe them without accepting any religious doctrine that contains it. Someone might, for instance, believe that Moses wrote the Torah in the Sinai desert without believing that God had anything to do with the matter.
Second, natural and supernatural elements are often tightly connected. For instance, though someone might believe that Moses wrote down the Torah but not believe that he did so under divine dictation, no one can believe that God dictated the Torah to Moses without believing that Moses wrote it down. That is a matter of logic. Other connections are a matter of psychology. Thus, while it is possible to believe, say, that a worldwide flood killed all land animals but those on Noah’s ark without believing that God had any hand in it, it is not likely that anyone—any adult of much education at any rate—would ever do so. That is, many natural religious beliefs are held only because of some accompanying supernatural religious belief.
Third, to the extent that a body of religious belief contains natural elements, it is subject to critical examination in the light of science. If it were established that the Torah was written down by Moses in the desert more than three thousand years ago, scientific investigation would be powerless to settle the question whether he was taking divine dictation. But the fact is that no such hypothesis is established, or, in view of the evidence, capable of being established. On the contrary, the findings of archaeological investigation as well as textual analysis render the belief that the Torah was written all at once, hundreds of years before the rise of the kingdoms of Israel and Judah, completely untenable. 
Fourth, even if the supernatural as such is beyond the reach of scientific criticism, mixed natural–supernatural beliefs are not. If it can be proved that the Torah was written hundreds of years after the time in which even the latest events recounted in it are purported to take place—which it can, unless one understands “prove” to signify a standard of certainty that is never attained in any empirical science—then the idea that Moses wrote it under divine dictation is also thereby refuted.
Fifth and finally—though this is not a point for which I shall be supplying the necessary argument in this entry—Judaism, like Christianity, is thoroughly dependent on natural beliefs and mixed natural–supernatural beliefs that are rationally untenable in the light of known evidence and scientific arguments. Even if purely supernatural beliefs, such as the belief in an almighty and supremely wise and benign creator and ruler of the universe, are given a free pass, specific natural and mixed beliefs are required for supporting a body of specific religious observances; and some of the most important of those beliefs are not rationally tenable.
 On the question of preserving versus establishing, see Menachem Kellner, Must a Jew Believe Anything? (London: Littman Library of Jewish Civilization, 2006).
 On archaeology, see Israel Finkelstein and Neil Asher Silberman, The Bible Unearthed: Archaeology’s New Vision of Ancient Israel and the Origin of Its Sacred Texts (New York: Free Press, 2001). On textual analysis of the Bible, see Richard Elliott Friedman, Who Wrote the Bible? (New York: HarperCollins, 1997).
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